The methylation of biogenic amines by 5-methyl tetrahydrofolate has been reported from several laboratories. We were able to show, however, that this was not a methylation reaction, but rather a non-enzymatic condensation of formaldehyde (generated by the "backwards" 5N, 10N-methylene tetrahydrofolate reductase) with the substrate amine. BIBLIOGRAPHIC REFERENCES: Meller, E., Rosengarten, H., Friedhoff, A.J., Stebbins, R.D., and Silber, R. 5-Methyltetrahydrofolic Acid is not a Methyl Donor for Biogenic Amines: Enzymatic Formation of Formaldehyde. Science 187:171-173, 1975.